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Chỉ định và Liều dùng
Intramuscular
Pernicious or macrocytic anaemia Adult: 250-1000 mcg, given on alternate days for 1-2 wk, then 250 mcg wkly until the blood count returns to normal. Maintenance doses: 1000 mcg, given every mth. Oral Megaloblastic anaemia caused by vitamin B12 deficiency Adult: 50-150 mcg daily. Oral Pernicious or macrocytic anaemia Adult: 2,000 mcg daily.
Child: 1,000 mcg daily or every 2 wk. |
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Suy thận
Intravenous:
Increased requirement in renal impairment. |
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Suy gan
Intravenous:
Increased requirement in hepatic impairment. |
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Cách dùng
Should be taken on an empty stomach. Take between meals.
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IM/IV/Nasal/Parenteral/SC: C
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Tác dụng
Description:
Mechanism of Action: Cyanocobalamin is vital to growth, hematopoiesis and nucleoprotein and myelin synthesis. As a hematopoietic agent, it is converted to coenzyme B12 needed in the conversion of methylmalonate to succinate and production of methionine from homocysteine, a reaction requiring folate. In the absence of folate, such metabolites cannot be formed and folate deficiency occurs. It is also involved in the maintenance of reduced sulfhydryl (SH) groups which are required by various SH-activated enzyme systems. Through such processes, cyanocobalamin participates in fat and carbohydrate metabolism as well as protein synthesis. Pharmacokinetics: Absorption: Binds to intrinsic factor secreted by gastric mucosa; via the GI tract actively or by passive diffusion. Distribution: In the blood, bound to transcobalamin II (specific B-globulin carrier protein); distributed and stored in the liver and bone marrow. Crosses the placenta and small amounts enter the breast milk. Excretion: via bile by enterohepatic recycling; via urine (as unbound B12 and in small fraction). |
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Phân loại MIMS
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